Stapling device with continuously parallel jaws

ABSTRACT

A stapling device includes first and second jaws. The second jaw defines first and second threaded bores. A drive member has a distal end portion supporting a rack. An approximation drive assembly includes a first lead screw received within the first threaded bore. A second lead screw is received within the second threaded bore. A first pinion is supported on the first lead screw. A second pinion is supported on the second lead screw. Moving the drive member from the retracted position toward the advanced position advances the rack to rotate the first pinion and the second pinion, the first lead screw within the first threaded bore, and the second lead screw within the second threaded bore to move the second jaw in relation to the first jaw from an open position to a clamped position.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patent application Ser. No. 16/872,701, filed May 12, 2020. The entire contents of which are incorporated herein by reference.

FIELD

This technology is generally related to surgical stapling devices and, more particularly, to surgical stapling devices that include a tool assembly including jaws in continuously parallel alignment.

BACKGROUND

Surgical stapling devices for simultaneously cutting and stapling tissue are known in the art and are commonly used during surgical procedures to reduce the time required to perform the surgical procedure and to facilitate endoscopic access to a surgical site. Performing a surgical procedure endoscopically reduces the amount of trauma inflicted on a patient during a surgical procedure to minimize patient discomfort and reduce patient recovery times.

Typically, endoscopic stapling devices include a tool assembly having a first jaw, and a second jaw that can pivot in relation to the first jaw between an open or spaced position and a closed or clamped position. One of the first or second jaws supports a cartridge assembly that includes a plurality of staples and the other of the first or second jaws supports an anvil assembly that includes an anvil having staple deforming pockets that receive and deform legs of the staples when the staples are ejected from the cartridge assembly.

In known devices, each of the first and second jaws is in pivotal relation with one another about a pivot point or hinge. Pivoting the first and second jaws creates mutually inclined surfaces in the first and second jaws, thus creating inconsistent pressure on tissue therebetween. As a result, tissue may be pushed toward a distal end of the first and second jaws upon closure of the jaws.

SUMMARY

This disclosure generally relates to surgical stapling devices, and more particularly, to surgical stapling devices that maintain a continuously parallel alignment between first and second jaws during closure of the first and second jaws. The tool assembly includes a rack and pinion closure mechanism. The rack and pinion closure mechanism is configured such that the second jaw is maintained in continuously parallel alignment with the first jaw as the first and second jaws are moved from an open configuration to a clamped configuration.

In one aspect of the disclosure, a tool assembly for a surgical stapling device includes a first jaw having a first surface and a second jaw having a second surface facing the first surface. The second jaw defines first and second threaded bores. The second jaw is movable in relation to the first jaw between an open position and a clamped position. A drive member has a distal end portion. The distal end portion supports a rack having a first side and a second side. The drive member is movable from a retracted position to an advanced position. An approximation drive assembly includes a first lead screw received within the first threaded bore. A second lead screw is received within the second threaded bore. A first pinion is supported on the first lead screw. A second pinion is supported on the second lead screw. The first pinion engages the first side of the rack and the second pinion engages the second side of the rack. The first lead screw and the second lead screw are each rotatably secured to the first jaw. Moving the drive member from the retracted position toward the advanced position advances the rack to rotate the first pinion and the second pinion. Rotating the first pinion rotates the first lead screw within the first threaded bore and rotating the second pinion rotates the second lead screw within the second threaded bore to move the second jaw in relation to the first jaw from the open position to the clamped position.

In some aspects of the disclosure, the second surface of the second jaw is maintained in substantially parallel alignment with the first surface of the first jaw as the second jaw is approximated from the open position to the clamped position. The first jaw supports first and second guide pins and the second jaw defines first and second orifices that are aligned with the first and second guide pins. The first guide pin and the second guide pin are configured to maintain substantially parallel alignment between the first surface of the first jaw and the second surface of the second jaw.

In some aspects of the disclosure, the first threaded bore is formed at least in-part in a first nut fixedly secured to the second jaw. The second threaded bore is formed at least in-part in a second nut fixedly secured to the second jaw.

In some aspects of the disclosure, the drive member includes a working end at the distal end portion of the drive member. The working end is configured to maintain a maximum distance between the first surface of the first jaw and the second surface of the second jaw when the second jaw is in the clamped position.

In some aspects of the disclosure, the working end of the drive member moves along the first jaw and the second jaw to maintain the maximum distance between the first surface of the first jaw and the second surface of the second jaw. The working end of the drive member defines an I-beam. The I-beam includes a first beam configured to be engaged with the first jaw a second beam configured to be engaged with the second jaw. A vertical strut connects the first beam and the second beam. The I-beam may include a distal-facing surface that defines a knife.

The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

Various aspects and features of the disclosure are described with reference to the drawings wherein like numerals designate identical or corresponding elements in each of the several views and:

FIG. 1 is a side perspective view of exemplary aspects of the disclosed stapling device including a tool assembly in an open position;

FIG. 2 is an enlarged side perspective view of the tool assembly of the stapling device of FIG. 1 ;

FIG. 3 is an exploded side perspective view of the tool assembly of the stapling device shown in FIG. 1 ;

FIG. 4 is a top plan view of the tool assembly of the stapling device shown in FIG. 1 with a first jaw shown in phantom and the drive member in a retracted position;

FIG. 5 is an enlarged side view of the tool assembly of the stapling device shown in FIG. 4 in the open position with the first jaw of the tool assembly shown in phantom;

FIG. 6 is a cross-sectional view taken along section line 6-6 of FIG. 5 ;

FIG. 7 is a cross-sectional view taken along section line 7-7 of FIG. 5 ;

FIG. 8 is a top plan view of the tool assembly of the stapling device shown in FIG. 1 in the clamped position with the first jaw of the tool assembly shown in phantom and the drive member in a partially advanced position;

FIG. 9 is an enlarged side view of the tool assembly of the stapling device shown in FIG. 8 with the first and second jaws of the tool assembly shown in phantom and the drive member in the partially advanced position;

FIG. 10 is a cross-sectional view taken along section line 10-10 of FIG. 9 ;

FIG. 11 is a cross-sectional view taken along section line 11-11 of FIG. 9 ;

FIG. 12 is a top plan view of the tool assembly of the stapling device shown in FIG. 1 in the clamped position with the first jaw of the tool assembly shown in phantom and the drive member in a fully advanced position; and

FIG. 13 is an enlarged side view of the tool assembly of the stapling device shown in FIG. 12 with the first and second jaws of the tool assembly shown in phantom and the drive member in the fully advanced position.

DETAILED DESCRIPTION

The disclosed surgical stapling device will now be described in more detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. However, it is to be understood that the aspects of the disclosure are merely exemplary of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the disclosure in virtually any appropriately detailed structure. In addition, directional terms such as horizontal, vertical, distal, proximal, and similar terms are used to assist in understanding the description and are not intended to limit the disclosure.

As used herein, the term “distal” refers to the portion of the stapling device that is being described which is further from a user, while the term “proximal” refers to the portion of the stapling device that is being described which is closer to a user. Further, to the extent consistent, any of the aspects and features detailed herein may be used in conjunction with any or all the other aspects and features detailed herein.

As used herein, the terms parallel and perpendicular are understood to include relative configurations that are substantially parallel and substantially perpendicular up to about + or −10 degrees from true parallel and true perpendicular.

“About” or “approximately” or “substantially” as used herein may be inclusive of the stated value and means within an acceptable range of variation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (e.g., the limitations of the measurement system).

Descriptions of technical features or aspects of the disclosure should typically be considered as available and applicable to other similar features or aspects of the disclosure. Accordingly, technical features described herein according to one exemplary aspect of the disclosure may be applicable to other exemplary aspects of the disclosure, and thus duplicative descriptions may be omitted herein.

FIG. 1 illustrates exemplary aspects of the disclosed surgical stapling device shown generally as stapling device 10. Stapling device 10 includes a powered handle assembly 12, an elongate body 14, and a tool assembly 16. The elongate body 14 defines a longitudinal axis “X-X” and includes a proximal portion 14 a supported on the handle assembly 12 and a distal portion 14 b that supports the tool assembly 16. In some aspects of the disclosure, the tool assembly 16 forms part of a reload assembly 18 that includes a proximal body portion 18 a that is adapted to be releasably coupled to the distal portion 14 b of the elongate body 14 of the stapling device 10. In other aspects of the disclosure, the proximal body portion 18 a includes a distal portion that supports the tool assembly 16 for articulation about an axis transverse to the longitudinal axis “X” of the elongate body 14. In alternate aspects of the disclosure, the tool assembly 16 is fixedly secured to the distal portion 14 b of the elongate body 14. For a description of exemplary aspects of the tool assembly, see, e.g., U.S. Pat. No. 6,241,139 (“the '139 patent”).

The handle assembly 12 of the stapling device 10 includes a stationary handle 20 and actuation buttons 22 that can be depressed to actuate the tool assembly 16, e.g., approximate the tool assembly 16, articulate the tool assembly 16, fire staples, etc. In aspects of the disclosure, batteries (not shown) are supported in the stationary handle 20 to power the handle assembly 12. It is envisioned that the stapling device 10 need not be powered but can also include a manually powered handle assembly such as described in the '139 patent.

FIGS. 2-13 illustrate the tool assembly 16 of the surgical stapling device 10 of FIG. 1 . The tool assembly 16 for the surgical stapling device 10 includes a first jaw 101 and a second jaw 102. In aspects of the disclosure, the first jaw 101 supports an anvil 111 that includes a first tissue contact surface 121, and the second jaw 102 supports a cartridge assembly 112 that includes a staple cartridge 113 defining a second tissue contact surface 122 and a plurality of staple pockets 114. Alternatively, the jaws of the tool assembly 16 may support other surgical devices including vessel sealing devices, clip appliers, two-part fastener appliers, grasping devices, etc. The second jaw 102 is movable in relation to the first jaw 101 between an open position (see, e.g., FIG. 2 ) and a clamped position (see, e.g., FIG. 9 ). In the clamped position, the second surface 122 of the staple cartridge 113 is in juxtaposed alignment with the first surface 121 of the anvil 111. As described below in more detail, in use, the second jaw 102 is moved from the open position to the clamped position by advancing a drive member 331, while continuously maintaining parallel alignment between the first surface 121 of the anvil 111 and the second surface 122 of the staple cartridge 113. When the second jaw 102 is in the clamped position, the first surface 121 of the anvil 111 and the second surface 122 of the staple cartridge 113 are in juxtaposed alignment and define a predetermined maximum tissue gap “G” (see FIG. 13 ).

Moving the second jaw 102 with respect to the first jaw 101 from the open position to the clamped position while continuously maintaining parallel alignment between the first surface 121 of the anvil 111 and the second surface 122 of the cartridge assembly 112 increases the ability of the operator to achieve a desired tissue compression force in the tissue gap “G.” Additionally, pinching of tissue which may occur around the site of a pivot point between an anvil and a cartridge in a conventional tool assembly can be minimized. Continuously maintaining the first surface 121 of the anvil 111 and the second surface 122 of the cartridge assembly 112 in parallel alignment applies a more evenly distributed compression force to the tissue during clamping, as compared with a conventional tool assembly employing a pivot point between the anvil 111 and the cartridge assembly 112.

FIGS. 3-7 illustrate the second jaw 102 which defines a first threaded bore 201 and a second threaded bore 202. The drive member 331 has a distal end portion 333 and a proximal end portion 332. The distal end portion 333 supports a rack 203 having a first side and a second side. The rack 203 defines a plurality of teeth on each of the first side and the second side of the rack 203 that are configured to engage gears formed on a corresponding pinion. An approximation drive assembly 204 (FIG. 3 ) includes a first lead screw 205, a second lead screw 206, a first pinion 207, and a second pinion 208. The first lead screw 205 is received within the first threaded bore 201 and the second lead screw 206 is received within the second threaded bore 202. A first pinion 207 is supported on the first lead screw 205 and the second pinion 208 is supported on the second lead screw 206. The first pinion 207 engages the first side of the rack 203 and the second pinion 208 engages the second side of the rack 203. The first lead screw 205 and the second lead screw 206 are each rotatably secured to the first jaw 101. Moving the drive member 331 from the retracted position toward the advanced position advances the rack 203 to rotate the first pinion 207 and the second pinion 208. Rotating the first pinion 207 rotates the first lead screw 205 within the first threaded bore 201 and rotating the second pinion 208 rotates the second lead screw 206 within the second threaded bore 202 to move the second jaw 102 in relation to the first jaw 101 from the open position to the clamped position.

The first threaded bore 201 may be formed at least in-part in a first nut 209 that is fixedly secured to the second jaw 102. Similarly, the second threaded bore 202 may be formed at least in-part in a second nut 210 fixedly secured to the second jaw 102.

The first jaw 101 supports a first guide pin 211 (FIG. 7 ) and a second guide pin 212. The second jaw 102 defines a first orifice 213 and a second orifice 214. The first orifice 213 is aligned with the first guide pin 211 and the second orifice 214 is aligned with the second guide pin 212. The first guide pin 211 includes a first end portion 215 partially positioned in the first orifice 213 when the second jaw 102 is in the open position with respect to the first jaw 101 (FIG. 7 ). The first end portion 215 of the first guide pin 211 further slides into the first orifice 213 as the second jaw 102 is approximated to the closed position with respect to the first jaw 101 (FIG. 11 ). The second guide pin 212 includes a second end portion 216 partially positioned in the second orifice 214 when the second jaw 102 is in the open position with respect to the first jaw 101 (FIG. 7 ). The second end portion 216 of the second guide pin 212 further slides into the second orifice 214 as the second jaw 102 is approximated to the closed position with respect to the first jaw 101 (FIG. 11 ). The first guide pin 211 and the second guide pin 212 maintain parallel alignment and prevent relative rotation between the first jaw 101 and the second jaw 102.

The distal portion 333 of the drive member 331 supports a working end (e.g., I-beam 334) that defines the maximum tissue gap “G.” The I-beam 334 has a first beam 335, a second beam 336, and a vertical strut 337 connecting the first beam 335 with the second beam 336. The drive member 331 is movable from a retracted positon (see, e.g., FIG. 5 ) towards a partially advanced position to move the tool assembly from the open position to the clamped position (see, e.g., FIG. 9 ), and is movable from the partially advanced position to a fully advanced position (see, e.g., FIG. 13 ) to fire staples from the cartridge assembly 112. The partially advanced position of the drive member 331 (FIG. 9 ) is defined by a distal end portion 339 of the rack 203. The drive member 331 has a flat surface 340 on opposite sides thereof between the distal end portion 339 of the rack 203 and the proximal end portion 332 of the drive member 331. Thus, advancing the drive member 331 from the partially advanced position (FIG. 9 ) to the fully advanced position (FIG. 13 ) does not rotate first pinion 207 or second pinion 208. When the drive member 331 is advanced from the retracted position (FIG. 5 ) to the partially advanced position (FIG. 9 ), the second jaw member 102 is fully approximated from the open configuration with respect to the first jaw member 101 (FIG. 5 ) into the approximated position with respect to the first jaw member 101 (FIG. 9 ) by rotation of the first pinion 207 and the second pinion 208. As the drive member 331 further moves through the tool assembly 16 from the partially advanced position (FIG. 9 ) to the fully advanced position (FIG. 13 ), the first beam 335 engages the first jaw 101 and the second beam 336 engages the second jaw 102 to prevent outward movement of the first and second jaws 101 and 102 beyond a pre-set distance to define the maximum tissue gap “G”. When the drive member 331 reaches the fully advanced position (FIG. 13 ), all staples of the cartridge assembly 112 have been fired.

The I-beam 334 may have a distal-facing surface that defines a knife 338 having a sharpened edge configured to cut tissue.

The various aspects of the stapling device disclosed herein may also be configured to work with robotic surgical systems and what is commonly referred to as “Telesurgery.” Such systems employ various robotic elements to assist the surgeon and allow remote operation (or partial remote operation) of surgical instrumentation. Various robotic arms, gears, cams, pulleys, electric and mechanical motors, etc. may be employed for this purpose and may be designed with a robotic surgical system to assist the surgeon during the course of an operation or treatment. Such robotic systems may include remotely steerable systems, automatically flexible surgical systems, remotely flexible surgical systems, remotely articulating surgical systems, wireless surgical systems, modular or selectively configurable remotely operated surgical systems, etc.

The robotic surgical systems may be employed with one or more consoles that are next to the operating theater or located in a remote location. In this instance, one team of surgeons or nurses may prep the patient for surgery and configure the robotic surgical system with one or more of the instruments disclosed herein while another surgeon (or group of surgeons) remotely controls the instruments via the robotic surgical system. As can be appreciated, a highly skilled surgeon may perform multiple operations in multiple locations without leaving his/her remote console which can be both economically advantageous and a benefit to the patient or a series of patients.

The robotic arms of the surgical system are typically coupled to a pair of master handles by a controller. The handles can be moved by the surgeon to produce a corresponding movement of the working ends of any type of surgical instrument (e.g., end effectors, graspers, knifes, scissors, etc.) which may complement the use of one or more of the aspects of the disclosure described herein. The movement of the master handles may be scaled so that the working ends have a corresponding movement that is different, smaller or larger, than the movement performed by the operating hands of the surgeon. The scale factor or gearing ratio may be adjustable so that the operator can control the resolution of the working ends of the surgical instrument(s).

The master handles may include various sensors to provide feedback to the surgeon relating to various tissue parameters or conditions, e.g., tissue resistance due to manipulation, cutting or otherwise treating, pressure by the instrument onto the tissue, tissue temperature, tissue impedance, etc. As can be appreciated, such sensors provide the surgeon with enhanced tactile feedback simulating actual operating conditions. The master handles may also include a variety of different actuators for delicate tissue manipulation or treatment further enhancing the surgeon's ability to mimic actual operating conditions.

It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device. 

What is claimed is:
 1. A tool assembly for a surgical stapling device, comprising: a first jaw having a first surface; a second jaw having a second surface facing the first surface, the second jaw defining first and second bores, the second jaw movable in relation to the first jaw between an open position and a clamped position; a drive member supporting a rack having a first side and a second side, the drive member movable from a retracted position to an advanced position; and an approximation drive assembly including a first lead screw received within the first bore, a second lead screw received within the second bore, a first pinion supported on the first lead screw, and a second pinion supported on the second lead screw, the first pinion engaging the first side of the rack and the second pinion engaging the second side of the rack, wherein movement of the drive member from the retracted position toward the advanced position advances the rack to rotate the first pinion and the second pinion, and wherein rotating the first pinion rotates the first lead screw within the first bore and rotating the second pinion rotates the second lead screw within the second bore to move the second jaw in relation to the first jaw from the open position to the clamped position.
 2. The tool assembly of claim 1, wherein the second surface of the second jaw is maintained in substantially parallel alignment with the first surface of the first jaw as the second jaw is approximated from the open position to the clamped position.
 3. The tool assembly of claim 2, wherein the first jaw supports first and second guide pins and the second jaw defines third and fourth bores that are aligned with the first and second guide pins, wherein the first guide pin and the second guide pin are configured to maintain substantially parallel alignment between the first surface of the first jaw and the second surface of the second jaw.
 4. The tool assembly of claim 1, wherein the first lead screw is arranged at least in-part in a first nut fixedly secured to the second jaw, and the second lead screw is arranged at least in-part in a second nut fixedly secured to the second jaw.
 5. The tool assembly of claim 1, wherein the drive member includes a working end at a distal end portion of the drive member, the working end configured to maintain a maximum distance between the first surface of the first jaw and the second surface of the second jaw when the second jaw is in the clamped position.
 6. The tool assembly of claim 5, wherein the working end of the drive member moves along the first jaw and the second jaw to maintain the maximum distance between the first surface of the first jaw and the second surface of the second jaw.
 7. The tool assembly of claim 6, wherein the working end of the drive member defines an I-beam, the I-beam including a first beam configured to be engaged with the first jaw, a second beam configured to be engaged with the second jaw, and a vertical strut connecting the first beam and the second beam.
 8. The tool assembly of claim 7, wherein the I-beam includes a distal-facing surface that defines a knife.
 9. A surgical stapling device, comprising: an elongate body having a proximal portion and a distal portion; and a reload assembly including a proximal body portion and a tool assembly, the proximal body portion adapted to be releasably coupled to the distal portion of the elongate body, and the tool assembly being supported on the proximal body portion, the tool assembly including: a first jaw having a first surface; a second jaw having a second surface facing the first surface, the second jaw defining first and second bores, the second jaw movable in relation to the first jaw between an open position and a clamped position; a drive member supporting a rack having a first side and a second side, the drive member movable from a retracted position to an advanced position; and an approximation drive assembly including a first lead screw received within the first bore, a second lead screw received within the second bore, a first pinion supported on the first lead screw, and a second pinion supported on the second lead screw, the first pinion engaging the first side of the rack and the second pinion engaging the second side of the rack, wherein movement of the drive member from the retracted position toward the advanced position advances the rack to rotate the first pinion and the second pinion, and wherein rotating the first pinion rotates the first lead screw within the first bore and rotating the second pinion rotates the second lead screw within the second bore to move the second jaw in relation to the first jaw from the open position to the clamped position.
 10. The surgical stapling device of claim 9, wherein the second surface of the second jaw is maintained in substantially parallel alignment with the first surface of the first jaw as the second jaw is approximated from the open position to the clamped position.
 11. The surgical stapling device of claim 10, wherein the first jaw supports first and second guide pins and the second jaw defines third and fourth bores that are aligned with the first and second guide pins, wherein the first guide pin and the second guide pin are configured to maintain substantially parallel alignment between the first surface of the first jaw and the second surface of the second jaw.
 12. The surgical stapling device of claim 9, wherein the first lead screw is arranged at least in-part in a first nut fixedly secured to the second jaw, and the second lead screw is arranged at least in-part in a second nut fixedly secured to the second jaw.
 13. The surgical stapling device of claim 9, wherein the drive member includes a working end at a distal end portion of the drive member, the working end configured to maintain a maximum distance between the first surface of the first jaw and the second surface of the second jaw when the second jaw is in the clamped position.
 14. The surgical stapling device of claim 13, wherein the working end of the drive member moves along the first jaw and the second jaw to maintain the maximum distance between the first surface of the first jaw and the second surface of the second jaw.
 15. The surgical stapling device of claim 14, wherein the working end of the drive member defines an I-beam, the I-beam including a first beam configured to be engaged with the first jaw, a second beam configured to be engaged with the second jaw, and a vertical strut connecting the first beam and the second beam.
 16. The surgical stapling device of claim 15, wherein the I-beam includes a distal-facing surface that defines a knife.
 17. A tool assembly for a surgical stapling device, comprising: a first jaw having a first surface; a second jaw having a second surface facing the first surface, the second jaw defining a first bore, the second jaw movable in relation to the first jaw between an open position and a clamped position; a drive member supporting a rack, the drive member movable in relation to the first jaw and the second jaw from a retracted position to an advanced position; and an approximation drive assembly including a first lead screw received within the first bore, and a first pinion supported on the first lead screw, the first pinion engaged with the rack, wherein movement of the drive member from the retracted position toward the advanced position advances the rack to rotate the first pinion, and wherein rotation of the first pinion rotates the first lead screw within the first bore to move the second jaw in relation to the first jaw from the open position to the clamped position.
 18. The tool assembly of claim 17, wherein the second jaw defines a second bore, and the approximation drive assembly includes a second lead screw that is received within the second bore and is engaged with the rack, and wherein rotation of the second pinion rotates the second lead screw within the second bore to move the second jaw in relation to the first jaw from the open position to the clamped position.
 19. The tool assembly of claim 18, wherein the first jaw supports first and second guide pins, and the second jaw defines third and fourth bores that are aligned with the first and second guide pins, the first guide pin and the second guide pin configured to maintain substantially parallel alignment between the first surface of the first jaw and the second surface of the second jaw.
 20. The tool assembly of claim 17, wherein the second surface of the second jaw is maintained in substantially parallel alignment with the first surface of the first jaw as the second jaw is approximated from the open position to the clamped position. 